The purpose of the proposed program is to identify components (either products or enzymes) specific to the acinar epithelial cells of the human prostate and to utilize these as markers to identify cells grown in culture. In addition, it is proposed to define conditions which will maximize the reproducible growth of acinar cells from explants in primary culture. Prostatic fluid obtained by massage will be fractionated by polyacrylamide gel electrophoresis to yield as many components as possible. Gels will be stained for protein, carbohydrates, lipids and also for specific enzymes. Fractions occurring in sufficient quantity and with adequate separation will be prepared as pure fractions by quantitative methods. These will be used to produce antisera which will be tagged with fluorescein isothiocyanate and used as reagents to strain frozen sections of prostatic tissue to localize the components coming from the acinar cells. These components specific to acinar epithelium will then be applied as markers to analyze growth in primary cultures and to follow population selection in continuously propagated cell lines.